My exposé when to use the word d*ck, c*ock, and p*nis:
Generally, I'd always use d*ck for referring to the male genitalia. It’s more pragmatic and practical. It can be used during coitus but it isn’t supposed to feel 100% salacious. Overall you can’t go wrong with d*ck, it fits everyone.
The word P*nis instead I wouldn’t use too often and mostly avoid them unless it is very very pragmatic. Like the scene in Down and Dirty where the MC says: »I can feel your d*ck” and the seme replies: “That is not my p*nis” -> this was perfect placement.
Now the best word of them all: c*ck. I feel like it has a very vulgar, obscene sub-emphasis and if used too often it loses this emphasis. So I’d say if there is dirty talk and it is really trying to be a turn-on that the word fits, but only if placed in moderation.
